What is definition of CXCR4 receptor?

CXCR4 shares features common to G protein coupled receptors. CXCR4 is a receptor for the CXC chemokine PBSF/SDF1 and functions as a co-receptor for HIV-1. CXCR4 is broadly expressed in the immune and the central nervous systems and can mediate migration of resting leukocytes and hematopoietic progenitors in response to SDF1. PBSF/SDF1 and CXCR4 define a signaling system for organ vascularization.